How Nuclear Fusion Reactors Work

Fusion Reactors: Inertial Confinement

­The National Ignition Facility (NIF) at Lawrence Livermore Laboratory is exp­erimenting with using laser beams to induce fusion. In the NIF device, 192 laser beams will focus on single point in a 10-meter-diameter target chamber called a hohlraum. A hohlraum is "a cavity whose walls are in radiative equilibrium with the radiant energy within the cavity" (Science & Engineering Encyclopaedia).

At the focal point inside the target chamber, there will be a pea-sized pellet of deuterium-tritium encased in a small, plastic cylinder. The power from the lasers (1.8 million joules) will heat the cylinder and generate X-rays. The heat and radiation will convert the pellet into plasma and compress it until fusion occurs. The fusion reaction will be short-lived, about one-millionth of a second, but will yield 50 to 100 times more energy than is needed to initiate the fusion reaction. A reactor of this type would have multiple targets that would be ignited in succession to generate sustained heat production. Scientists estimate that each target can be made for as little as $0.25, making the fusion power plant cost efficient.